Probability → Basics → Vocabulary → Probability Formula
The probability of an event can be calculated by the proportion (or probability) formula
For example, in the basic probability vocabulary page, the question was,
A coin is tossed two times. What is the probability that both times the head was occurred?
Here, the sample space is
And, the favorable event, or an event for which we want to find probability is . This event is 1 among the total 4 events. Hence, and . The probability that both of the events are “heads” is thus
A fair dice is rolled once. What is the probability that an even number is occurred?
If a dice is rolled, any number from 1 to 6 can occur. So, the sample space is
And even numbers are three: 2,4,6. So favorable events () are 3, and total events () are 6. Hence,